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Q. I'm installing 1,200 square feet of flooring in an older home and am considering using a power booster. How do I know if I need one? Is it safe?
A. Whether or not to use a power booster depends on the job and the job site. This may seem like a simple answer to a fair question, but the job may or may not need more power.
A common problem on many job sites is that all of the trades use the same source for power. All of the equipment and various machines are plugged in to one power supply on a common pole in the middle of the job site. If this is the case, you may need to run 200 feet or more of cable to the location where your work is being done. If the voltage drops below 220 volts, you will need to use a power booster. Also, because several different trades are using power from one source, it's common for the breaker to trip. I've seen heated arguments over whose equipment is tripping the breaker.
Other job sites, such as old homes, older parts of town and rural areas, may not have enough power. Some of these job sites may only have 208 volts as the supply.
The big machine, some buffers and multi-disc sanders need enough voltage to start up and reach proper run speeds. Low voltage causes the motors to run hot, labor and, in some cases, damage the fields or capacitors. It even may burn the motor up, which is a very costly repair or replacement to have to make. Low voltage also may lead to imperfections in the floor, such as wave or chatter, or enhance dish-out of the soft grain in the wood.
Checking the voltage with a Voltage Ohm Meter (VOM) before and after you hook up your machines is a step that many flooring contractors often forget or just don't do at all. You should test the line for a few simple, but important, demands of the motor. First, make sure each leg or line is the same, or paired, as some electricians refer to it. A 220-volt line consists of one earth ground and two 110-volt inputs. If the two 110-volt lines are not paired, then damage may occur to the motor. If you test only the complete input, you won't know if voltage is needed on one side of the power line. For example, one leg could test at 120 volts and the other 100 volts. Together the two lines are 220 volts, but the weak leg could damage the motor. Make sure you test each leg with the ground and not just the total input (voltage).
Another thing to watch for is a high leg, which is one leg of the power supply that is increased. This is common in some electric stoves, dryers and HVAC systems. A high leg may overload the motor on your big machine. A high leg also can burn up plugs and connectors and, in extreme cases, could catch on fire. The only way to prevent this damage to your machine is by taking the time to test the power supply with a VOM.
If you get a voltage reading that is too high, such as 245 to 250 volts, many machines have a buck feature that reduces, or bucks, the power. They can reduce the power by 10 to 15 percent, bringing the power down to 220 to 225 volts, allowing full and constant feed to the motor. Another trick to reduce the voltage is to add cable until the power drops to the correct voltage. Make sure you have a VOM to ensure the voltage reaches an optimal level.
A power booster is a safe way to get correct voltage. Using the correct size wire and hookup is the best and safest way to use a power booster. The National Electric Code provides guidelines for safe hookup. If your power booster does not have 110-volt outlets, then you do not need to worry about the guidelines for four-wire hookup. However, if your unit has 110-volt outlets, you need to make sure you are not using the earth ground as the neutral wire. The ground wire has two guidelines—it must be the same size as the input wires and it must carry only the fault current. If you are using a three-wire unit with 110-volt outlets, you should have a service center install the correct plug for four-wire hookup, or remove the 110-volt outputs. Incorrect use of the unit may shock the person operating the tools. The four-wire units have two hot leads, one earth ground and one neutral line. This is the only safe use of a power booster with 110-volt outlets. You will need 10–4 wire as the supply into the power booster and 10–3 wire for the output. If you or your crews are unsure of the correct hookup, pay an electrician. Include this expense in the bid and explain to the homeowner that this will ensure safe operation of the sanders as well as safety of the home.
A power booster is a very important tool and, if used correctly, is a safe one. To boost or not to boost is simple—use the VOM and let it tell you if you have too much or not enough power.